Shrinkproofing process



Patented Feb. 16, 1943 UNITE' E. I. du Pont de Nemours &

Company, Wilmington, DeL, a corporation of Delaware No Drawing. Application March 19, 1940, Serial No. 324,869

2 Claims. (Cl. 8-128) This invention relates to the improvement of wool and other keratinous textile fibers, and

more particularly to processes for reducing the shrinking tendency of such fibers.

A number of keratinous textile fibers, of which wool is the most important. are characterized by their tendency to felt when subjected to mechanical working. This tendency is essential in the finishing of some woolen goods to give a dense sistant to shrinkage. on laundering. The materials which have been employed for this purpose are the free halogens, hypohalous' acids, inorganic and organic hypohalites, and certain N-halogenated organic compounds such as the N-chloroamides and imides. These substances contain the group XY'where X is halogen, divalent oxygen, or singly-bonded tervalent nitrogen, and Y is halogen. All of these have usually been applied from aqueous-or alcoholic solutions. In all cases the effective agent is believed to be active halogen with a valence of plus 1 in the hypohalous acid liberated'by the treating substance on contact with water. Even where a halogen gas or a non-aqueous solution is used on normally air-dried wool, it is believed that the wool contains sufficient moisture to liberate the required quantity of hypohalous acid, 1. e. active halogen of valence plus 1, to bring about shrinkproofing.

The serious disadvantages encountered in the commercial practice of present chlorination processes have, however, greatly inhibited the commercial usefulness of these methods. Thus, chlorinated wool generally is unevenly. treated, harsh, and badly tendered, as indicated by decreased tensile strength and wearing qualities. In the continuous treatment of piece goods, the difflculty of tailing'is encountered, that is,overtreatment of the first part of the fabric entering tion has been proposed specifically, but has also not achieved complete success.

, the bath and undertreatment of the latter part. In an effort to overcome the unfavorable efiects encountered with chlorinating agents, brominatextile fibers by reducing their tendency to shrink on laundering. A further object is the production of wool of decreased tendency to shrink which is free from harshness, discoloration, and loss of strength. A still further object is to provide a new and improved halogenating process for reducing the shrinking tendency of wool.

These objects are accomplished by the following invention wherein a keratin-containing animal fiber, e. g., wool, or a mixture of such fiber with other textile material is subjected to the action of a halogena'ting substance, 1. e., a substance liberating active halogen, i. e., a substance liberating halogen having a valence of plus 1, i. e., a substance which produces a hypohalous acid on contact with water, i. e., a substance containing halogen of atomic weight greater than 21 attached directly to halogen, divalent oxygen, or singly-bonded tervalent nitrogen, e. g., free halogen, hypohalous acids, inorganic and organic hypohalites, and certain N-halogenated organic compounds, such as the N-chloroamides and the N-chloroimides, in the presence of an organic compound containing at least one ether oxygen bonded to carbons which are in turn attached to,

hydrogen and carbon only, the carbons attached to the same ether oxygen atom not being attached to each other.

In carrying out the process of this invention, wpol or wool-containing textile material is immersed in a dilute solution of a halogenating agent in the ether solvent. The length of the treatment may be varied in accordance with the concentrations ofv the reagents used. However, as described in the following examples, a period of 0.5 to 1.0 hour is preferred, and the concentrations are so adjusted that a satisfactory treatment is obtained in this period.

It is preferred to treat the textile material attemperatures within the range most conveniently obtained under practical operating conditions, i. e., between 5 and 50 C. Higher temperatures are less preferred because of the increased volatility of some preferred ether solvents and the danger of accelerating the treatment to a less easily controllable rate. Lower temperatures are difiicult to obtain and cause decreased solubility of the halogenating agents, with the exception of The treatment is most the halogens themselves. conveniently begun at room temperature, or only slightly above, the reaction being exothermic to a slight degree.

After treatment, the excess solution is removed by wringing, centrifuging, or rinsing. It is often desirable to apply a dehalogenating agent such as sodium thiosulfate to the treated wool, in order to remove any excess uncombined treating agent.

The halogenating agent is generally used entirely in solution in the ether solvent, and best results are obtained in this way. However, agents of limited solubility can be used in suspension with good results. It is preferred to use the, pure ether solvent'as asolvent or suspending medium for the halogenating agent, but mixtures with other solvents which do not destroy the efficiency of the agent, such as alcohols, water, or inert organic liquids may be used. This procedure is advantageous in employing gaseous or solid ether compounds, though it is preferred that the ether solvents be liquids at ordinary temperatures. Where a mixed solvent is used, a substantial proportion of the ether solvent should be employed. It is preferred that such mixtures contain at least 20% by weight of the ether solvents. The concentration of the halogenating agent will vary with the agent used, but is usually below In general it is preferred to apply the treatments to normal air-dry wool, i. e.,-wool with a moisture content of approximately 8 to 20%. Halogenation treatments are ineffective in shrinkproofing bone-dry wool. I

In determining the effect of the treatment on the shrinking tendency of wool, it has been found convenient to use a uniform testing procedure, referred to hereinafteras the laundering test. In this test equal areas are marked on a small sample of wool fabric treated according to this invention and on a sample of otherwise similar,

untreated fabric, respectively. Then each is passed a definite number of times (usually 150) through a rubber-roll wringer, dipping after each Pass into an aqueous solution at 77 F. containing 0.1% sodium carbonate and 0.25% of a sulfated oleyl alcohol preparation. Other dilute alkaline soap solutions can be used in this test. After laundering, the samples are dried and again measured. The area losses sustained by the samples are determined and the per cent reduction in shrinking tendency is calculated from the following formula:

lOOX (area loss of untreated fabric-area loss of treated fabric)- (Area loss of untreated fabric) Percent reduction of tendency to shrink The figures given in the following examples are determined by this method. The laundering test is also a convenient method for following the treatment, since a small sample may b taken from the textile material which is immersed in the halogenating solution at the end of a period judged to be suitable for obtaining the desired effect and tested in the above manner to determine the per cent reduction in shrinking tendency. If the material has not yet been treated to the desired degree, the process may be continued until another test indicates that the desired shrinkproofness has been achieved.

The more detailed practice of the invention illustrated by the following examples, wherein parts given are by weight. There are of course many forms of the invention other than these specific embodiments.

Example I One part of wool flannel which has been conditioned overnight in a chamber maintained at 77 F. and 50% relative humidity is immersed at 95 F. in 5.6 parts of a 2.7% solution of N-chlorocaprolactam in dioxane. The sample is removed after one hour and the excess treating solution is wrung out. The wool is then immersed for live minutes in 4% aqueous sodium bisulfite solution and rinsed in water. The flannel is free from discoloration and is very soft and strong. The wool is substantially shrinkproof, the tendency to shrink having been reduced 84%.

Example II One part of wool flannel which has been conditioned at 77 F. and 50% relative humidity is immersed at 95 F. in 5.5 parts of a 3.65% solution of N.N'-dichloro-5,5-dimethylhydantoin in immersed at 95 ethylene glycol dimethyl ether. After one hour the sample is removed and freed from the excess solution. The fabric is then rinsed thoroughly in water. The laundering test shows that the shrinking tendency of the flannel has been reduced 83% as compared to a value of 11% for the same flannel treated under identical conditions except that benzene is used as the solvent.

Example III One part of wool flannel which has been conditioned at 77 F. and 50% relative humidity is F. in 5.7 parts of a 3.5% suspension of N ,N'-dichloro-5,5-dimethylhydantoin ,in

ethylene glycol monobutyl ether. After one hour the wool is removed and freed from the excess treating solution. It is then rinsed thoroughly in water. The laundering test shows that the shrinking tendency of the sample has been reduced 78.5% as compared with a value of 20% for a similar sample treated under identical conditions except for the substitution of ethylene dichloride as solvent.

Example IV One part of wool flannel which has been conditioned in a chamber maintained at 77 F. and 50% relative humidity is immersed in 6 parts of a 4.25% suspension of sodium N-chloro-p-toluene-sulfonamide (Chloramine T) in dioxane at F. The wool is removed after one hour, freed from excess solution, and rinsed thoroughly in water. The shrinking tendency of the flannel is reduced 50% as a result of this treatment. which does not discolor the fabric. Repetition of the experiment in which water is substituted for dioxane yields a severely browned sample, the shrinking tendencyof which is reduced only 15%.

Example V One part of wool flannel which has been. conditioned in a chamber maintained at 77 F. and 50% relative humidity is immersed in 5.5 parts of a 3.65% solution of N,N'-dichloro-5,5-dimethylhydantoin in anhydrous ethylene glycol dimethyl ether at 95 F. The fabric is removed after two hours, freed from the excess treating solution, and rinsed thoroughly in water. The laundering test shows the fabric to be completely shrinkproof.

Example VI One part of wool flannel which has been conditioned in a chamber maintained at 77 C. and 50% relative humidity is immersed in 5.0 parts of a 3.9% solution of N,N'-dichloro-5,5-dimethylhydantoin in a solvent consisting of 4 parts by volume of 95% ethyl alcohol and 1 part by volume of ethylene glycol dimethyl ether. The solution is at 95 F. when the sample is immersed. After 1.5 hours, the material is removed, freed from the excess solution, and rinsed thoroughly in water. The sample is evenly treated, free from discoloration, and substantially shrinkproof.

0n repeating the experiment and using a sol- Example VII One part of union fabric having a cotton warp and a wool woof and conditioned in a chamber maintained at 77 F. and 50% relative humidity is immersed at 77 E. in 11.6 parts of an acidified aqueous hypochlorite solution to which 2.5 parts of ethylene glycol dimethyl ether has been added. The hypochlorite solution is prepared by adding sulfuric acid to bleaching powder and contains 0.5% available chlorine. After 20 minutes, the fabric isremoved, rinsed in water and then in 2.5% aqueous sodium thiosulfate solution. The treated fabric is soft, untendered, and 88% re duced in shrinking tendency.

When the same treatment is applied, except that ethylene glycol dimethyl ether is omitted from the treating bath, the resulting product is markedly harsh and tendered.

Edzample VIII One part of wool flannel which has been conditioned in a chamber maintained at 77 F. and 50% relative humidity is immersed in 6 parts of dioxane at 77 F. containing 0.65% dissolved chlorine added to the solution in the form of a saturated carbon tetrachloride solution. After one-half hour, the wool is removed and the sample is rinsed thoroughly in water. 7 For comparison, a similar sample of wool flannel is immersed after identical conditioning in 4.4 parts of Stoddard solvent (A. S. T. M. specification: D484-38T) at 77-F. containing 0.83% dissolved chlorine. After one-half hour, the wool is removed and the sample is rinsed thoroughly in water.

The wool chlorinated in dioxane (shrinking tendency having been reduced approximately 60 per cent) is soft and lofty in handle, whereas the .wool chlorinated in Stoddard solvent, though shrinkproof, shows a marked deficiency in these desirable qualities.

Example IX One part of wool flannel conditioned in a chamber maintained at 77 F. and 50% relative humidity is immersed at 77 F. in 4.55 parts of a 4.4 per cent solution of N,N'-dichloro-5,5-dimethylhydantoinin diethyl ether which also contains 1.6 per cent methanol. After 1 hour, the wool is removed and rinsed thoroughly in water. The flannel, whose tendency to shrink is reduced by half, is soft, free from discoloration, andevenly treated.

Ezmple X halogenating substance known to the shrinkequivalent thereto containing acproofing art or tive halogen, i. e., having halogen of atomic weight greater than 21 attached to halogen, singly-bonded tervalent nitrogen, or divalent oxygen, e. g., the free halogens, inorganic and organic hypohalites, hypohalous acids. and certain'N-halogenated organic nitrogen compounds. Substances in which the active halogen is chlorine are-preferred over the bromineand iodinecontaining substances because of economic advantages and the greater stability of the active chlorine compounds on storage. Active fluorine compounds are excluded from the processes of this invention. Organic compounds having chlorine linked to amido nitrogen, i. e., N-chloroand N,N-dichloroamides and N-chloroimides of carboxylic and suifonic acids are particularly preferred because of their efiectiveness and par ticularly easily controlled affect. Specifically preferred are the N-chloro cyclic amides, i. e., N-chloro lactams and hydantoins. The inven tion is generic to the use of the above substances containing active halogen attached to halogen, divalent oxygen, or singly-bonded tervalent nitrogen, including specifically chlorine gas, bromine, or iodine, dissolved in water'or organic solvents, sodium hypochlorite, sodium Nechlorop-toluenesulfonamide, N.N-dichloro-p-toluenesulfonamide, tert-butyl hy'pochlorite, amyl hypochlorite, N-chlorocaprolactam, and N,N'-dichloro-5,5-dimethyl hydantoin. \N,N-dichloro-5,5-dimethyl hydantoin is preferred above all as'the chlorinating agent, since it is. very highly effective, easily controlled, stable in storage, and readily soluble in the preferred solvents.

N-chlorocaprolactam is another very efiective agent and may be prepared conveniently by passing chlorine into an ice-cooled solution con:

taining 300 parts of water, 67 parts of caprolactam, and 52 parts of sodium carbonate until 48 parts of the gas has been absorbed. quires approximately 45 minutes. The yellow oil which forms is separated, washed with water, and dried over sodium sulfate. This compound boils at 138 C./l5 mm. pressure.

Calculated for CcHioClNO: Cl, 24.08. Found: Cl, 24.74. In view of its thermal instability, it is advisable to use N-chloro-caprolactam without prior distillation.

In some cases, it may be desirable to accelerate the action of the chlorinating agent. This may be done by adding small portions of a salt formed from a strong base and a weak acid, such as sodium acetate.

In the process of the invention there may be used in combination with the wool halogenating agent any ether or polyether containing only carbon, hydrogen and singly bonded oxygen wherein each ether oxygen is attached to two carbons not attached to each other and attached only to hydrogen and/or carbon, including dialk yl, arylalkyl, diaryl, diaralkyl, cyclic, and polyethers, for example, diethyl ether, methyl amyl ether, ethyl benzyl ether, dibenzyl ether, anisole, phenetole', diphenyl ether, dioxan, tetrahydrofurane, ethylene glycol dimethyl ether,

ethylene glycol monomethyl ether, triethylene glycol dimethyl ether, methyl lauryl ether. betaethoxyethanol, diethylene glycol monoethyl ether, betaphenoxyethanol, beta-butoxyethanol, and diamyl ether. The ethers liquid at normal temperatures are preferred. Aliphatic ethers containing only carbon, hydrogen, and ether oxygen are especially preferred.

Compounds containing more than one other linkage, such as the dimethyl ether of ethylene glycol, are particularly preferred because they are, in general, particularly good solvents for the This repreferred halogenating agents. The radicals attached to ether oxygen may also contain other.

functional groups, provided they are not attached to carbon atoms which are directly attached to the ether oxygens. Thus, ether-alcohols, such as the monomethyl ether of ethylene glycol may be used. However, the functional groups should not be such as to react rapidly with and destroy the efllciency of the halogenating agent. Alpha-alkylene oxides, i: e., cyclic ethers having a ring consisting of two carbon atoms and one oxygen atom, e. g., ethylene oxide, are not included. These can not be used because they react readily with halogenating agents and thus their effectiveness is destroyed.

The process of the present invention is generically applicable to keratinous fibers and to mixtures comprising keratinous fibers with other textile fibers, whether the fibers be a textile, yarn or woven goods. While the process is particularly applicable to and shows best results with textiles of which a major proportion is wool or other keratinous fiber, it is also applicable to textiles containing minor, though substantial, proportions of keratinous fibers. Wool is the principal keratinous fiber, but the invention is applicable to all keratinous textiles. Thus, other ke'ratinous fibers such as rabbit fur characterized by the tendency to felt may be improved in like manner by the processes of this invention. The treatment is preferably applied to woven or knitted goods either in the piece or in the form of socks, sweaters, jackets, coats, bathing suits, scarfs, dresses, suits, baby clothing, and blankets. e

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The process of the present invention gives evenly treated products which are not tendered,

discolored or hardened as are the products of earlier halogenation processes. Furthermore, it is possible to obtain much better efiects in the later finishing processes such as dyeing which may follow the shrinkproofing treatment. The wool wears better and has a higher tensile strength.

The ether solvents enhance the eflectiveness of certain N-chloro organic compounds. Thus, a N,N'-dichloro-5,5-dimethylhydantoin, satisfactory as a shrinkprooflng agent when applied from dioxane, is nearly plied from benzene. Furthermore, the ether solvents readily dissolve this preferred chlorinating agent, and the clear solutions thus obtained avoid deposits on the textile fibers.

The above description and examples are intended to be illustrative only. Any modification of or variation therefrom which conforms to the spirit of theinvention is intended to be included within the scope of the claims.

What is claimed is:

1. Process for improving a woolen textile which comprises treating the same with a chlorinating agent dissolved in a solvent comprising dioxane, said chlorinating agent being one which liberates hypochlorous acid in contact with water.

2. Process for improving a woolen textile which comprises treating the same with N,N'- dichloro-5,5-dimethylhydantoin dissolved in a solvent comprising dioxane.

' PAUL ARTHUR. JR.

without effect when ap- 

